Air conditioning control apparatus



Dec. 29, 1953 E. M. MILLER 2,664,244

AIR CONDITIONING CONTROL APPARATUS Filed May 16, 1950 p K as '26 TINVENTOR.

E.M. MILLER A TTORNE Y5 Patented Dec. 29, 1953 OFFICE AIR CONDITIONINGCONTROL APPARATUS Enoch Merle Miller, Bartlesville, Okla., assignor toPhillips Petroleum Company, a corporation of Delaware Application May16, 1950, Serial No. 162,308

7 Claims.

This invention relates to air conditioning systems and a means ofcontrol therefor. In one of its aspects, it relates to moclutrol motorsadaptable to be employed in an air conditioning system and to a meansfor remotely controllin such motors. In another of its aspects, thisinvention relates to a means for controlling a plurality of inodutrclirotors from a single remote control unit. In still another of itsaspects, this invention relates to a snap-acting switch especiallyadapted to be employed in a modutrol motor control system.

Modutrol motors for controlling the opening or closing of dampers,refrigerant control valves, heating medium control valves and the likeduring the heating or cooling cycle of an air conditioning system, arewell-known in the art. In such an air conditioning system which isadapted to function the year round to provide suitable heating duringthe winter months there must be provided a means for converting themodutrol motors from winter operation to summer operation. For example,during the Winter months, the function of the modutrol motors is to opena valve controlling the heating medium flowing into an air conditioningsystem or space whenever the temperature in the conditioned spacedecrease During such period, the motor may have an additional functionof opening conditioned air dampers to each space in order to provideadditional heating in such space. In those systems where the temperatureof the conditioned air is controlled by the admission of cold fresh airfrom a point external of the system, it is a function of the motors todecrease the amount of air, for example, whenever the temperature insidethe conditioned spaces decreases. During summertime operation, thefunction of th modutrol motor is opposite to that during wintertimeoperation. temperature in the air conditioned spaces, it is necessaryfor the modutrol motors to close a valve controlling the introduction ofrefrigerating medium into the air conditioning apparatus. C-r, where themodutrol motors control the opening and closin of dampers into an airconditioned space, the motor must close the damper whenever thetemperature within such space decreases.

Accordingly, as stated, it is necessary to convert the operation or themodutrol motors from one function for wintertime operation to anopposite function during summertime operation. In the prior art, suchconv sion has been accomplished by manually convei m each modutrol motorin Thus, with a decrease in the air conditioning system at the timechangeover from wintertime to summertime operation and at the timechangeover from summertime to wintertime operation is made. Such achangeover system has many disadvantages. For example, in an ordinaryair conditioning system in a large building Where there will ordinarilyexist a great many modutrol motors, perhaps even hundreds of them, it isnecessary to convert each motor individually from one type of operationto the other so that such conversion is necessarily very time consuming.In addition, in many parts of the country where the weather is extremelychangeable, it would be highly desirable to have the modutrol motorsalternately on wintertime and summertime operation for short periods oftime during the year. Thus, in the spring and fall there will be manydays when it will be necessary to cool the air conditioned spaces andmany succeeding days When it Will be necessary to heat such spaces. Itmay even be desirable to heat the spaces early in the morning and tocool them during the noontime heat. Obviously, in such systems Wherethere are hundreds of modutrol motors where each must be manuallyconverted from one type of operation to the other, such short timechangeover is not feasible. Accordingly, it would be highly desirable inthe air conditioning art to possess a means for changing modutrol motorsfrom heating operation to a cooling operation wherein such meansfunction in a very short period of time with a minimum of manual laborand can be switched from one type of operation to another upon a momentsnotice.

t is an object of this invention to provide an air conditioningapparatus which can be readily converted from a heating to a coolingoperation, or vice versa.

It is another object to provide a means for converting modutrol motorsfrom a heating operation to a cooling operation or vice versa Within aminimum time and with a minimum of expense.

It is another object of this invention to provide a means for convertinga plurality of modutrol motors from a heating operation to a coolingoperation or vice versa at a single point remotely removed therefrom.

It is still another object of this invention to provide a means forconvertin a plurality of modutrol motors from a heating operation to acooling operation, or vice versa.

Yet another object is to provide a snap-acting switch especially adaptedto be employed in the modutrol apparatus of this invention.

Various other objects, advantages and features or the enuion will becomeapparent from the following description taken in conjunction with theace-can, anylng rawings, in which:

l is a diagrammatic sketch of an air conditioning system employing theapparatus of this invention. Figure 2 is adiagrammatic illustration of aportion oithe apparatus shown in Figure 1.

Referring now to Figure l, a plurality of spaces I to 3 are to beindividually air conditioned by means of conditioned air passing throughconduits is and it from blower l2. TheairrDassing through conduit ii isheatedcr cooled, as desired, by means of coil l3, which contains asuitable heath or cooling medium in a manner well-known to the art.Valve 3 is'provide'd to control the rate of admission of heatingoryccoling medium to coil l3. Dampers 5 to 22 are situated. in openingsfrom ducts 9 and is into each or" the individual spaces which areto beair conditioned and serve to control the amount of conditioned airadmitted to each of these spaces.

Operativeiy connected to each of thedampers by means of linkages 23 to33, aredainpe' actuating units 31 to "v'alve id is connected by means oflinkage 35 to an actuating mechanism Actuating mechanisms 3% to E8 andso are termed modutrol motors and comprise a reversible electrical motoroperatively connected to the linkages 23 to and so that the dampers orvalves connected to such linkages can be opened and closed dependinguponthe direction of rotation of the electrical motor. The direction of.rotation of the electrical motor is controlled by controlling mechanismshown in detail inFigure 2.

Referring to Figure 2, theapparatus within the dashed outline iicorresponds to the actuating mechanisms-"3! to 38 and d3 of Figure 1 andelectric motor $2 is connected through gears to an operatm linkage dwhich, in turn, is operated to open and close the valves or dampers asabove-described. A temperature-sensitive mechanism is connected by meansof linkage to wiper arm ii which is pivoted about a point is and formsan electrical contact -39 with a control variable impedance such asresistance 53. The temperature-sensitive means i5 can be any one ofvarious types welldinown to the art, such as an extendable bellowsfilled with a thermally expansible fluid. Motor 52 is connected to wiperarm 55 by means of linkage 52 and actuating gear in such fashion thatrotation of motor 22 will cause wiper 5! to move back and forth across abalancing variable impedance such as resistance thereby varying theposition of contact point So of wiper arm ti on such resistance.

A snap-acting relay switch designated generally as 55 is employed as adouble-throw, doublepole switch adapted to reverse the direction ofcurrent flow through resistance as. Relay 53 is comprised of amagnetizable core 5? which can have a C-shape to form a gap 58 therein.Coil 59 is situated around a portion of the armature to act as amagnetizing means therefor. Situated in gap 53 of armature i3? is apivoted permanent magnet 69 which is biased about pivot point ti bymeans of spring 52 so that magnet til will be urged by spring 62againstone or the other of the ends of armature 5'5, as shown.Extendingiirom magnet 59 are contact arms 63 and 8d having situated ontheir ends contact points 55 and A contact member t? is comprised ofelectrically conductive contact strips or material 58, so, is and ii,each of these strips of material being in- *cohtrol variable impedanceconditioned skilled in the art.

;turn,..is.connected to one end of coil sulated one from the other bymeans of insulating medium '52 and a central insulating block it. Thecontact member can be formed in an are about pivot point B! of magnet 68so that contact points 65 and 65 can swing back and forth along abuttingcontact strips $8 and it and along $9 and! l respectively, toestablishcontact with said contact members.

End '53 of resistance 55 is connected by means of wire it to contactstrip ii and by means of wire #6 to contact strip 63. The opposite endii ofresistance 555 is connected by means of wire "55 .to contact stripl8 and by means of wire is to contact: strip .59.

A relaymeans is provided to be actuated by an unbalanced condition ofcurrent flow through and balancing variable impedance 5%. The relaymeans will then actuate motor 2 to cause it to rotate in such adirection as to rebalance the circuit comprising impedances it ended toopen or close means for correcting the changed condition in the'air ence. The relay means has a U-shaped permanent magnet having north andsouth poles, as shown, which is-mounted to pivot aboutp-oint Si by meansor arms PE. Opposite and adjacent each pole of magnet 88 are situatedel-ectrornagnets 33 and 8 3. One end oi lectromagnet'SB is connected bymeans of wire 81 to sli'deable contact 65 and one end of electromagnet64% is connected by means of wire 33 to the opposing slideable contactThe opposite end of'electromagnet 83 is connected by wire 59 to one endof resistance 55 while the other end of electromagnet as is connected bywire 3i? to the other end of resistance 59, 'as'sh-own.Electromagnetsilt and 84 are wound in such a direction that electricalenergy flowing from resistance through lines 89 and 38 will cause themto be magnetized in such a manner that both will either attractor repelthe pole of magnet 38 opposite therefrom. Thus, any unbalancedmagnetization of electromagnets sfiand as will cause a ro- "tative forceto be exerted against the poles of magnet in such a manner that it willcause rotation about pivot point 8 l Attached to supporting arms 82 isan elongated member 9: bearing contact points 92 and 93 at its end, asshown. For the sake of clarity of illustration, coil 94 and coil 95 areshown as separate coils in Figure 2, however, coils 9d and 95 actuallyform'the field coils of motor 42 and are so arranged in the motor thatwhen current is flowing through coil il the motor will rotate in onedirection but when current is flowing through coil 25 the motor willrotate in an opposite direction. The ends of coils Stand 95 areconnected to con 'tact'points Stand Ell, as shown.

Aysource ofD. C. power 9S,'which can be a battery or other meanswell-known to the art, is connected by means or wires 535-3 and to adoublethrow, ;double-polez.switch iti. Switch ifil, .as shown, isadapted to reverse the polarity of wires 1G2 and H33. in a mannerwell-known to those Wire it? can lead to a plurality of the actuatingmechanisms as shown in Figures 1 and .2, each of which is connected tothe wire I62 by means .of a wire lfiIZA, which,.in The other end of coil.59 is connected by meansof wire N34 to wire 595, which connects theends of coils 9d and 95 to wiper arm 5i. Wire 5% is connected to wireE66 by means or" wire lill. Alternatively, wire I53 can be grounded ascan be wire A91, thereby eliminating the necessity of employing twowires to each of the actuating mechanisms, as shown in Figure 2 to useonly a single wire I02 and a ground I 03A as shown in Figure 1.

In discussing the operation of the apparatus of this invention, assumethe air conditioning system is in summertime, i. e. cooling service.Hence, upon an increase in temperature in air conditioned spaces I to 8,it will be necessary for modutrol motor 42 to open valve I4 to admitadditional cooling medium to coil I3. Or, modutrol motors BI to 38 willopen dampers I5 to 22 in order to permit more cooled air to enter theair conditioned spaces. Referring in particular to Fi ure 2, assume thatswitch IIH is thrown to the right so that wire 39 is connected to wireI02 and assume, further, that wire I02 is negative with respect to wireI03. Further, assume that the wiper arms 4! and BI are positioned alongresistances 5|! and 54, respectively, in such a manner that resistanceR1 equals resistance R; and rea sistance R2 equals resistance R4.Current will flow through wire I02 and wiper arm 4! and be divided atcontact point 49 so that an equal amount of current will now throughelectromagnets 83 and 84, respectively. As a result, electromagnets 83and 84 will exert a balanced force against the poles of magnet 53,thereby 1naintaining contact arm SI and contact points 52 and 93 in anintermediate and non-contacting position with respect to contact points95 and 97. Current leaving electromagnet 33 ii-ows through wire 81,contact arm 63, contact strip E3 and, thence, through wire It toterminal i i of resistance 54. Current leaving electromagnet 84 flowsthrough wire 88, contact arm 5 contact strip 69 and then through wire I9'to terminal i? of resistance 54. The current flowing through resistance54 from each of terminals TI and M will flow through wiper arm 5|, wire87, coil 59 and then through wire IIlZA back to the source of current98. Coil 59 is so wound as to magnetize armature 5'! and attract magnet69 to the position shown in the drawing. Thus, in effect, equal amountsof current flow through each of electromagnets 83 and 84 and throughresistances R3 and R4 when the control apparatus for motor 42 is in abalanced position.

Now assuming that the temperature in an air conditioning spaceincreases, temperature-sensitive element 45 will expand pushing wiperarm 4! to the left, thereby increasing resistance R4 with respect toresistance R3. As a result, more current will flow through R3 andelectromagnet 83 than through R and electromagnet B4. The increasedcurrent flowing through electromagnet 83 with respect to electromagnet84 causes magnet 80 to pivot about point 8 I, thereby contacting contactpoints 93 and 91 to permit current to flow through wire I lit, contactarm 9| to coil 95 which, as stated, is a field coil of motor 42. As aresult, motor 42, operating through linkage 44, act to open arefrigerant valve or a damper in order to decrease the temperature inthe air conditioned space. In so doing, the motor also pushes wiper arm5! to the right and will continue to do so until R1 equals R4 and R2equals R3 thereby again balancing the circuit so that the currentflowing through electromagnet 83 again equals that flowing throughelectromagnet 84 and contact point 93 is separated from contact point81, thereby stopping the motor. With a decrease in temperature in theair conditioned space, a reaction opposite to that described above willtake place, resulting in energization of field coil 94 of motor 42 sothat the motor will rotate in an opposite direction to close therefrigerant valve or the damper.

When it is desired to convert the control mechanism, shown in Figure 2,to wintertime operation. that is, to control motor 42 so that it willclose a heating medium control valve or close a damper with an increasein temperature in an air conditioned space, it is necessary to merelythrow switch IOI to the poles opposite those described above. That is,in the case of this example, switch IGI will be thrown to the left sothat wire I02 becomes positive with respect to wire I03. In so doing,the polarity of coil 58 is reversed and the poles of armature 51 arelikewise reversed, so that magnet 69 i attracted to a position oppositethat shown in the drawing. In reversing the polarity of armature 5?,magnet 68 is held in the position shown spring 62 until the polarity iscompletely reversed and the electromagnet attraction has increasedsumciently to attract magnet Gil to a position opposite that shown inthe drawing and to overcome the reaction of spring 62. As magnet ispulled from the position shown in the drawing, the contact points oncontact arms 63 and E8 slide along contact strips I0 and H withoutbreaking the established circuit until they reach insulating materialI3. After the aforesaid contact points reach insulating material 73,spring 62 will be in a neutral position with respect to its pivotingforce upon magnet 6t. Immediately after the contact points leaveinsulating material it, spring 62 acts to exert a force on magnet 69,which complements the force exerted thereon by the reversed polarity ofarmature 5?, thereby causing magnet 50 to snap into its new positionopposite that shown in the drawing. With this manner of construction,the snap-acting double-throw, double-pole electromagnetic switch iscapable of maintaining a circuit during the greater proportion of thtime which elapses in changeover from one position to another positionand the action of spring 62 is such that th switch is given a snapaction.

After the polarity of the balancing variable impedance means has beenreversed, that is, the terminals 14 and I? of balancing variableimpedance 54 have been reversed with respect to control variableimpedance 59 so that terminals I4 and I! are disconnected fromelectromagnets S3 and 84, respectively, and connected to electromagnets84 and 83, respectively, as above dcscribed by placing snap-actingswitch 56 in a position opposite to that shown in the drawing, currentflowing through line Hi2 and line I84 and wiper arm 5| will be dividedat contact point 55 when the control mechanism is in a balanced positionand equal amounts of current will flow through R1 and R2. The currentflowing from Rs through wire IE will flow through contact strip 10 and,thence, out through wire 8? to electromagnet 83. Current flowing from E1through line 18 flows through contact strip 15 and wire 88 toelectromagnet 84. The current flowing from the electromagnets will thenpass through the wires 89 and 99 and R3 and R respectively, throughwiper arm 4? and then through wire I 0'2 back to the source of current98. If it is assumed that the temperature in the air conditioned spaceincreases so that temperature-sensitive element 45 pushes wiper arm 5'!to the left, a greater amount of current will flow through wire 8S andelectromagnet 83 than through wire as and ele tromagnet 84, therebycausing magnet to rotate in such a manner that coil 9d of motor 42 is.energized to rotate the motor to: close the damper or the heating mediumcontrol valve. In sorotating, wiper arm Will bepulled to the left untilit reaches a position such that R1 equals R3 at which point the currentflowing through electromagnets 83 and 5 will be equal, thereby breakingthe circuit to the field coil 9 of the motor 42.

It will be obvious from the foregoing description of the apparatus ofthis invention that it is possible to control, i. e. to convert fromsummertime to wintertime operation or vice versa, a great many modutrolmotors by duplicating for each motor the apparatus shown in the broadportion of Figure 2. ihese motors can be scat.- tered over m ny floorsor a large building. lIhus, when employing the apparatus of thisinvention, it will be a simple matter to convert these units fromwintertime to summertime operation or vice Versa by merely throwingswitch id! to one position or the other to reverse the polarity ofmodutrol motors and Without necessarily having to manually convert eachindividual motor to an opposite polarity by mechanically changing theleads to the modutrol motor, as is now the practice.

Still further, it will be possible to more closely control an airconditioning system when employing the apparatus of this inventionbecause, as stated, it will be possible to convert the modutrol motorsfrom one type or operation to the other as many times per day as iswished whereas such conversion is not possible with the systems now inuse because of the physical impossibility of manually converting eachmodutrol motor from one type of operation to the other. This particularfeature of this invention is highly advantageous in climates which areextremely changeable and is particularly advantageous during the springand fall when the weather in almost any climate may be cool one day andhot the next.

While the invention has been described in connection with presentpreferred embodiments thereof, it is to be understood that thisdescription is illustrative only and is not intended to limit theinvention, the scope of which is defined by'the appended claims.

I claim:

1. A control system for a motor which comprises, in combination, areversible motor, a normally balanced circuit comprising two normallybalanced impedance paths, an electromagnetic relay associated with saidimpedance paths adapted to reverse the direction of rotation of saidmotor responsive to an unbalanced condition of said impedance paths,means for unbalancing said impedance paths, means responsive to therotation of said motor for rebalancing said impedance paths, a switchfor reversing the polarity of one of said impedance paths with respectto the other of said impedance paths and said electromagnetic relay andmeans for-actuating-said switch.

2. In a control system for a motor, a reversible motor, a normallybalanced circuit having two normally equal impedance paths, anelectromagnetic relay controller controlling said motor and adapted tocause said motor to be reversed in direction of rotation responsive, toan unbalanced condition or said impedance paths, means f'orvarying therelative impedance of said impecance paths to unbalance said circuit,means responsive to the r tation of said motor for rebalancins saidimpedance paths, an electromagnetic switch for reversing the polarity ofmeans for rebalancing said impedance paths, and means for reversing theposition of said electromagnetic switch.

3. In combination, a device to .be positioned in a plurality ofpositions to control the value of a condition, control variableresistance means, means responsive to changes in the value of thecondition to be controlled for adjusting automatically said controlvariable resistance means, relay means for controlling the operation ofsaid device, balancing variable resistance means operated by saiddevice, connections between said. relay means, said control variableresistance means and said balancing variable resistance meansforpositioning said device in accordance with changes in the valuev or.the condition to be controlled, means for changing the polarity of saidbalancing variable resistance means with respectto said relay means and.means for reversing the polarity of said control variable resistancemeans, said relay means and said balancing variable resistance means.

l. In combination, a device to be positioned. in a plurality ofpositions to control the value of a condition, control variableimpedance means, means responsive to changes in the value of thecondition to be controlled for adjusting automatically said controlvariable impedance means, relay means for controlling the operation ofsaid device, balancing variable impedance means operated by said device,connections between said relay means, said control variable impedancemeans and said balancing variable impedance means for positioning saiddevice in accordance with changes in the value of the condition to becontrolled, means for changing the polarity of said balancing variableimpedance means with respect to said relay means and means for reversingthe polarity of said control variable impedance means, said relay meansand said balancing variable impedance means.

5. An air conditioning system for a building having a plurality ofspaces, which comprises, in combination, an air conditioning unitadapted to deliver heated or cooled air to each of said spaces, a motorcontrolled damper for each of said spaces for regulating the volume ofair delivered thereto in accordance with the temperature in said space;a plurality of motor control means each associated with one of saidmotors to there by control the opening and closing of each damper eachor" which comprises a normally balcircuit having a control variableimped ance means responsive to changes in temperature in said space,relay means for controlling the direction of rotation of said motor,balancing variable impedance means operated by said motor,

connections between said relay means, said control variable impedancemeans and said balancing variable impedance means adapted to per nitsaid relay to control the direction of rotation of said motor responsiveto the variation in impedance oi'sa'id control variable. impedance meansand being further adapted to cause said motor to vary the impedance ofsaid balan g variable impedance means in such a manner that said circuitwill become balanced thereby stopping the rotation of said motor, meansfor reversing the polarity of said balancing impedance means withrespect to: said relay means andsaidcontrol impedance-means; and asingle means'ior reversing thepolarity of said control. variable:impedance means, said relay means and said balancing variable impedancemeans in each of said plurality of motor means associated with each ofsaid motors,

6. The apparatus or" claim 5 wherein the means for reversing thepolarity of said control variable impedance means, said relay means andsaid balancing impedance means comprises a double throw, double-poleswitch adapted to reverse the polarity of a source of direct currentwith respect to the aforesaid means.

7. The apparatus of claim 5 wherein the means for reversing the polarityof said balancing impedance means with respect to said relay means andsaid control variable impedance means comprises a snap-acting switchadapted to operate in response to a reversal in polarity of a source ofdirect current with which said switch is connected in a two wire system.

ENOCH MERLE MILLER.

10 References Cited in the file of this patent UNITED STATES PATENTSNumber Name Date 2,036,277 Johnson Apr. 4, 1936 2,132,960 Montrose-OsterOct. 11, 1938 2,177,597 Haines Oct. 24, 1939 2,196,687 Steinfield Apr.9, 1940 2,269,036 Nessell Jan. 6, 1942 2,274,614 Nessell Feb. 24, 19422,294,210 Roters Aug. 25, 1942 2,418,395 Carlson a- Apr. 1, 19472,437,726 Davis Mar. 16, 1948 OTHER REFERENCES "Electronic Computers byWilliam Shannon- Electronics, pp. 110 to 113, August 1946.

